/Engine/Source/Runtime/Engine/Classes/PhysicsEngine/PhysicsConstraintComponent.h
Pass in reference frame in. If the constraint is currently active, this will set its active local pose. Otherwise the change will take affect in InitConstraint.
void SetConstraintReferenceFrame ( [EConstraintFrame::Type](API\Runtime\PhysicsCore\Chaos\EConstraintFrame__Type) Frame, const FTransform & RefFrame )